1. Field of the Invention
The present invention generally relates to an electronic spectrometer for identifying element conditions of a sample surface by utilizing an energy spectrum of charged particles, e.g., an Auger electron spectrum and a photoelectron spectrum, and more particularly to a photoelectron spectrometer in which photoelectrons emitted from the sample surface by irradiating X-rays having a specific wavelength are energy-analyzed by a detector to identify the element conditions of the sample surface.
2. Description of the Prior Art
A photoelectron spectrometer as described in the preamble is well known in the field. In FIG. 1A, there is shown a cross-sectional view of a conventional photoelectron spectrometer; in FIG. 1B, a plan view thereof. Referring to FIGS. 1A and 1B, an electron gun 1 for exciting X-rays, a target 2, a crystal plate 3, a sample 4, a neutralizing electron gun 5, an electron analyzer 6 and a detector 7 are positioned substantially in a coplanarly. The electron gun 1 emits an electron beam 8 and irradiates it to the target 2.
When irradiated by the electron beam 8, the target 2 emits X-rays 9a omnidirectionally. The functions of the crystal plate 3 positioned substantially midway between the target 2 and the sample 4 are: firstly to collect the X-rays 9a emitted from the target 2; and secondly to separate only X-rays 9b having a specific wavelength; and finally, to irradiate these X-rays 9b to the sample 4 by reflecting them. Upon receipt of the X-rays having the specific wavelength from the crystal plate 3, photoelectrons 10 are omnidirectionally emitted from the sample 4. Only the photoelectrons 10 which are traveling toward a specific region of dimension are conducted to an inlet of the electron analyzer 6. The electron analyzer 6 energy-analyzes the thus conducted photoelectrons 10 and thereafter supplies the energy-analyzed photoelectrons 10 to the detector 7.
The detector 7 identifies the elements contained in the sample 4 by detecting the photoelectrons supplied from the electron anaylzer 6. The neutralizing electron gun 5 irradiates electron beams 11 toward the sample 4 in a shower form so as to neutralize the surface of the sample 4 which is charged to a positive condition in accordance with the emission of the photoelectrons 10.
In the above-described conventional analyzer, since the components are arranged in a coplanarly, the X-ray irradiation and the detection of the photoelectrons 10 are implemented in a coplane. That is to say, as the crystal plate 3 is positioned at one side, viewed from the target 2, the X-rays 9a omnidirectionally emitted from the target 2 are partially utilized for the photoelectron analysis. The partial X-rays 9a pass through a specific region which is defined by an angle of ".alpha." radians (referred to as "detectable opening angle .alpha.") in a horizontal plane and by an angle of ".beta." radians (referred to as "detectable circle angle .beta.") in a vertical plane. Normally, this region covering the detectable opening angle .alpha. nearly equals to the detectable circle angle (0.1 to 0.3). Similarly, only the photoelectrons 10 omnidirectionally emitted from the sample 4 are partially conducted into the electron analyzer 6, because the hemispherical electron analyzer 6 has the inlet directing to a given direction, as shown in FIG. 1A.
Accordingly, the sensitivity of the photoelectron detection is very low, resulting in an extremely long time for analyzing the element conditions of the sample surface. Moreover, due to a lack of sensitivity, it is practically impossible to analyze a very small content, or a very small part of a sample.
Althrough not shown in detail in the drawings in FIGS. 1A and 1B, the through holes, through which the electron beams pass, may cause disturbances of the electric field as well as the magnetic field, so that precise photoelectron analysis can be disturbed.
To solve the above-described conventional drawbacks, an object of the present invention is to provide an electronic spectrometer by which the X-rays as well as the charged particles that are omnidirectionally emitted from the target and the sample respectively are more efficiently utilized to analyze the sample at the highest sensitivity.
Another object of the invention is to provide a photoelectron spectrometer in which the photoelectron spectroscopy can be implemented at a narrow region while maintaining the practical sensitivity.
A further object of the invention is to provide an electronic surface analyzer in which the sample analysis can be performed by utilizing the spectrum analysis without receiving adverse influences from leakage electric field and also leakage magnetic fields. This electronic surface analyzer can analyze a sample having a concave and convex surface with practically acceptable sensitivity.